Arrangement for cooling the poles of a dynamoelectric machine

ABSTRACT

An arrangement for cooling the pole shoes of a leg-type pole dynamo electric machine includes a metal frame which is arranged on and surrounds the pole core between the pole coils and the pole shoe. The metal frame which lies in direct contact with the pole shoe is provided with internal channels through which a liquid coolant is circulated and also constitutes a closed loop which thereby also establishes a single-turn short circuit winding on the pole core.

United States Patent ARRANGEMENT FOR COOLING THE POLES OF ADYNAMOELECTRIC MACHINE 1 Claim, 1 Drawing Fig.

US. Cl 310154, 310/64 Int. Cl 11021: 9100 Field of Search 310/54, 59,

References Cited UNITED STATES PATENTS 3,230,487 1/1966 Pellecchia310/197 1,715,866 6/1929 Rother 310/58 2,722,616 11/1955 Moses 310/542,749,457 6/1956 Kilner 310/64 3,032,665 5/1962 Wilhelmson.... 310/543,154,706 10/1964 Richardson 310/54 3,157,806 11/1964 Wiedemann 310/643,463,952 8/1969 Norris 310/5 8 Primary Examiner-D. F. Duggan AssistantExaminer-R. Skudy Attomey-Pierce, Scheifler & Parker ABSTRACT: Anarrangement for cooling the pole shoes of a leg-type pole dynamoelectric machine includes a metal frame which is arranged on andsurrounds the pole core between the pole coils and the pole shoe. Themetal frame which lies in direct contact with the pole shoe is providedwith internal channels through which a liquid coolant is circulated andalso constitutes a closed loop which thereby also establishes asingle-tum short circuit winding on the pole core.

mmcmm I "3533054 3 EEEE INVENTOR. ugen W/edemmnn g I Pe zr VoAdmimstrdor ARRANGEMENT FOR COOLING THE POLES OF A DYNAMOELECTRICMACHINE This invention relates to dynamoelectric .machines and moreparticularly to an improvement in the means for cooling the pole shoesof such a machine in which the poles are of the leg type. y

In the case of dynamoelectric machines having poles of the leg type andwherein insulation must always be provided between the pole coils of thefield winding and the pole iron, the heat due to energy losses producedin the iron of the pole shoes can only be eliminated by way of theairgap or through the pole core. The pole coil itself absorbs only aninsignificant portion of this heat even in the case where the coil iswound from tubular conductor material through which a fluid coolant iscirculated to conduct the heat away.

In dynamo electric machines of the foregoing type, considerabledifferences in temperature can therefore appear between the pole shoeand the field winding, particularly in the case of an asynchronous startof the machine, and these temperature differences exert a considerablestress on the intermediate insulation. Moreover, the pole may undergoconsiderable bending caused by the different expansions of pole shoe andpole core, which can lead to increased stresses on the pole claws andfinally to loosening of the pole mounting. All these phenomena are aresult of a too slow elimination of the heat from the pole shoe.

The principal object of the invention is thus to provide an improvedarrangement for cooling the pole shoes of a leg-type pole machine bymeans of a fluid coolant, particularly a liquid, which results in a veryeffective heat elimination so that the above-mentioned thermalexpansions, which occur in the case of the previously known coolingarrangements, are avoided. This objective is attained in that a liquidcooled metal frame surrounds the pole leg in direct contact with thepole shoe and located between the latter and the field winding coil onthe pole leg. I

A preferred embodiment of the invention will now be described and isillustrated in the accompanying drawing in which the pole shoe with theimproved cooling arrangement is shown in longitudinal section.

With reference now to the drawing, the core portion of the field pole ofthe machine is indicated at l and is seen to be provided with coils 2 ofthe field winding which are electrically insulated from the pole core bylayers of insulation 3. The coils 2 can consist, for example, of tubularconductors which are directly cooled by means of circulating a coolantliquid through the interior channels 2a. A metal frame 5 is located onthe pole core 1 between the coils 2 and the pole shoe 4 and is seen tobe in direct contact with the surface of the pole shoe. The frame 5which can be made from bronze is likewise provided with interiorchannels 6 through which a coolant liquid is circulated, the liquidserving to rapidly carry away the heat produced in the pole shoe. Thechannels 6 in the frame 5 and the channels 2a in the field winding coils2 are preferably connected up to the same cooling system. The frame 5 isalso preferably designed as a closed, i.e. a loop element surroundingthe pole core thus to constitute a single turn short-circuit winding.

The rapid and very effective elimination of the heat generated in thepole shoe due to loss of energy, which is achieved with theabove-described construction results in the following essentialadvantages.

Successive asynchronous starts of the machine in shorter intervals thanheretofore are readily possible.

The temperature differences on both sides of the insulation providedbetween the pole coils and the core remain very small, so that themechanical stresses of the insulation due to unequal thermal expansionsremain negligible.

The otherwise required strong cooling air along the pole shoe surfacecan be substantially reduced.

If the metal frame between the pole shoe and pole coils is designed as aclosed, short-circuit winding, a part of the starting energy is producedin the frame itself so that the pole shoe is relieved.

The efficiency of the machine is increased and greater safety isachieved which is of paramount importance particularly in frequentlyutilized machines having a great core length, for example, in motorgenerators for pump storage stations.

1 claim:

1. In a dynamoelectric machine of the type having leg-type poles andpole shoes thereon at the ends of the poles, the improvement whichcomprises a flat metallic frame forming a loop surrounding the poledirectly beneath and in direct contact with a flat face of the poleshoe, a channel provided within and extending around said frame andthrough which a liquid coolant'is circulated thereby to effect removalof heat from said frame and hence also from said pole shoe, anenergizing coil of the hollow conductor type surrounding the leg portionof said pole and through which a liquid coolant is circulated aninsulating layer provided between said energizing coil and said metallicframe and a further insulating layer provided on the leg portion of saidpole for insulating said leg portion from said metallic frame and alsofrom said energizing coil.

1. In a dynamoelectric machine of the type having leg-type poles andpole shoes thereon at the ends of the poles, the improvement whichcomprises a flat metallic frame forming a loop surrounding the poledirectly beneath and in direct contact with a flat face of the poleshoe, a channel provided within and extending around said frame andthrough which a liquid coolant is circulated thereby to effect removalof heat from said frame and hence also from said pole shoe, anenergizing coil of the hollow conductor type surrounding the leg portionof said pole and through which a liquid coolant is circulated, aninsulating layer provided between said energizing coil and said metallicframe and a further insulating layer provided on the leg portion of saidpole for insulating said leg portion from said metallic frame and alsofrom said energizing coil.